Cups-browsed cannot bind to port 631 as non-root user on Ubuntu 23.04
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
cups-browsed (Ubuntu) |
Fix Released
|
Undecided
|
Till Kamppeter |
Bug Description
After upgrading to Ubuntu 23.04, my laptop failed to discover our print server.
The problem seems to have been caused by a new change in cups-browsed that was added to Ubuntu 23.04.
I looked into it and found a small fix that seems to solve my issue.
Using the debug configuration for cupsd and cups-browsed, I looked through the logs and noticed the following line:
failed to bind CUPS Browsing socket: Permission denied
After reading more about printer advertisement and cups-browsed, I concluded that the printer is shared to my Ubuntu 23.04 laptop via CUPS on port 631.
When I connected an Ubuntu 22.04 laptop to the WIFI network, I saw the printer really was being shared with CUPS on port 631.
Cups-browsed was running as root on 22.04 while on 23.04 it is running as a new user - cups-browsed, but this new user didn't seem to have the necessary permissions to open a listening socket on port 631.
The solution I tried was granting the relevant binding permissions to the binary with this command (on the 23.04):
setcap cap_net_
After giving the permissions, my computer successfully discovered the printer, just like it used to on 22.04!
I think the command should be added to the post install script or maybe the capability should be granted to the new cups-browsed user.
I posted it as an issue in the CUPS project on github. They told me to post it here because its an Ubuntu issue: https:/
Related branches
- Till Kamppeter: Pending requested
-
Diff: 17 lines (+2/-1)1 file modifieddebian/patches/0002-run-cups-browsed-as-user.patch (+2/-1)
tags: | added: udeng-2092 |
The attachment "Add CAP_NET_ BIND_SERVICE capability to cups-browsed binary" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.
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